1. Field of the Invention
The present invention relates to the field of wafer fabrication and panel display technology, and more specifically, to a thin-film transistor (TFT) array substrate and the method of forming the same.
2. Description of the Prior Art
In most cases, a semi-conductor layer in a TFT is composed of metal oxide films, which are extremely sensitive to acid. Even a weak acid can quickly erode the oxide semi-conductor layer. Therefore, the oxide semi-conductor layer is easily damaged in the process of etching a metal source electrode and drain electrode on it.
In addition, given that an oxide semi-conductor layer is thin, usually between 30 nm to 50 nm, it takes only a few seconds, even with a diluted hydrofluoric (HF) acid solution having a concentration of 500:1, to etch the oxide semi-conductor layer. However, most metal requires a strong acid and long period of time to be etched. Thus how to etch a metal source electrode and drain electrode on an oxide semi-conductor layer becomes a difficulty that must be overcome immediately.